This invention relates in general to gas detection devices and in particular to a new and useful gas detection measuring device into a gas measuring and warning device.
The invention relates particularly to developments of a gas measuring and warning device described in German patent application P 35 01 093.2-52, which is not a prior publication.
Such a gas measuring and warning device contains a test tube traversed by the gas to be detected as well as a photoelectric sampling means for the test tube illuminated or irradiated by at least one source of light and it comprises a photo-sensitive row of similar sensor elements for observation of a reaction zone migrating through the test tube. Connected to the photoelectric sampling means is an evaluating circuit, which is controlled by the sensor elements lying inside the reaction zone for delivery of a measurement signal. The photoelectric sampling means further contains an imaging optical system which projects the test tube onto the photosensitive row of the sensor elements for delivery of an analog output signal.
For the delivery of low noise signals from the row of the sensor elements it is necessary to design the imaging optical system so that as high as possible a light intensity occurs on the surface of the row of sensor elements, combined with a good quality of reproduction. In addition, the reproduction error of the imaging optical system is to be kept small over the entirelength of the row of sensor elements and in particular also in the edge regions. All of the measures named below thus serve to provide a photoelectric sampling means, and in particular, the imaging optical system contained therein, that a low-noise high-resolution measurement signal can be taken from the row of the sensor elements.